http://www.airsoftmechanics.com/home...nt/view/19/26/
This should clear up all you're questions. low end ammunition (cheap), achieves low end results, period. Sometimes a poor performing gun can be traced to low end ammunition. I'm not going to go into great detail about the Magnus effect- (what you're hop up does to the BB) that is applied to the BB every time it leaves a barrel, but an unbalanced BB (inconsistent air bubble dispersion throughout the BB) has no predictable flight path, especially when the Magnus effect is applied to it. Want to improve you're groupings kiddies?..stop buying in bulk at Walmart.